An illustration of Sikorsky's presidential helicopter bid, which is based on its successful S-92 commercial helo. (Sikorsky)

WASHINGTON — It’s looking increasingly likely that when the bidding closes Thursday afternoon for the new VXX presidential helicopter program, only one serious offer will be made.

Of the three major industry teams expected to compete, two — AgustaWestland and Bell-Boeing — have announced their withdrawal, leaving the field to Sikorsky.

That’s not the way the Navy, which is managing the program, wanted it. “Industry feedback was given serious consideration throughout the RFP [request for proposal] refinement process with the goal of maximizing participation from interested bidders,” Capt. Cate Mueller, a Navy spokeswoman at the Pentagon, said in a statement.

Italy’s AgustaWestland, partnered with Northrop Grumman, had planned to offer a U.S.-built version of its AW101 helicopter. While the effort seemed to be moving ahead, the company decided a few weeks ago to end its bid before submitting an offer.

Reported first in Sunday’s New York Times, AgustaWestland issued a terse statement.

“After a comprehensive analysis of the final RFP, we determined we were unable to compete effectively given the current requirements and the evaluation methodology defined in the RFP. There are fundamental proposal evaluation issues that inhibit our ability to submit a competitive offering, and that provide a significant advantage to our likely competitor.

“The decision to withdraw was most difficult, as we believe we have the best, most capable aircraft for the president and the one selected in the prior competition. Fair and meaningful competition for major U.S. government programs is absolutely essential to providing the most capable products for an affordable price.”

Agusta’s U.S. partner, Northrop Grumman, declined to elaborate.

“As a team with AgustaWestland, we opted not to participate in the VXX program,” Northrop spokesman Randy Belote said, deferring further comment to Agusta.

Boeing also admitted it was ending its effort to offer versions of its H-47 Chinook twin-rotor helicopter or the Bell-Boeing V-22 Osprey tiltrotor aircraft.

“The Boeing Company will not submit a bid for the U.S. Navy’s VXX Presidential Helicopter program,” company spokesman Damien Mills said in a statement. “While both the Boeing H-47 Chinook and the Bell-Boeing V-22 are often used to transport military and government leaders in theaters of operation, we do not believe these aircraft would be competitive for this program as it is currently structured.”

The Navy declined to comment on the situation.

“Until the window closes for VXX proposals Aug. 1, the Department of the Navy does not know, and it is of no consequence — no consequence at all — to speculate what companies will submit bids,” Mueller said in a statement.

“A draft RFP was released in November 2012 and updated throughout the refinement process. In addition, site visits and several group and one-on-one forums were held to receive feedback from interested vendors,” she said.

“The acquisition approach includes a full and open competition to contract for integration of mature subsystems into an air vehicle that is currently in production as the most affordable VXX solution.”

While price is a key factor in the decision, none of the competitors has revealed its cost proposals, and the Navy is prohibited from doing so until the winner is announced sometime next year.

Sikorsky would only confirm that it is still in the VXX game.

“Sikorsky and partner Lockheed Martin are proud to respond to the request for proposals for the VXX Presidential Helicopter Replacement program,” company spokesman Frans Jurgens said in a statement. “We have prepared our proposal anticipating a full and open competition against other industry teams. We firmly believe we have the ideal team to deliver the best aircraft, on time and within budget.”

While no one would comment for the record, several industry and government sources observed that the lack of a second bidder was not welcome.

“No competitors invites more scrutiny,” one industry observer said.

“Major proposals can cost up to $200 million,” another industry source noted. “A lot of companies aren’t going to waste that kind of money chasing proposals without a better chance to win.”

The first VXX competition was won by a Lockheed Martin-AgustaWestland team, which beat out a Sikorsky proposal. But the Lockheed effort fell afoul of severe cost growth — largely because of increasing requirements from the White House and Secret Service — and the effort was canceled in June 2009. Lockheed, which lobbied furiously in the first VXX program to play down foreign-built aspects of the Italo-English US101, subsequently announced its intention to partner with Sikorsky in a renewed effort.

But other programs using foreign-based aircraft designs have failed, despite attempts by most bidders, including Europe-based Airbus and Brazil’s Embraer, to structure their proposals to embody more made-in-the-USA features.

Northrop had been partnered with Airbus in a high-profile effort to build an aerial refueling tanker for the Air Force — at one point winning the contract only to have it overturned on protest — losing out eventually to Boeing in 2011.

VXX bids close Thursday at 2 p.m. Eastern time. The Navy is not expected to provide additional information after that deadline.